Comparing Energy Efficiency in Supermarkets using CO2 & R507 Date: July 15th, 2018 Table of Contents 1 Introduction ................................................................................................................... 3 2 Purpose of the Study ..................................................................................................... 4 2.1 Purpose ..................................................................................................................... 4 2.2 Parameters Measured ............................................................................................... 4 2.3 Geographic Location ................................................................................................ 5 3 Implementation.............................................................................................................. 6 3.1 Equipment Used ....................................................................................................... 6 3.2 Hardware Installation ............................................................................................... 7 4 Project Background Information ................................................................................ 8 4.1 Temperature Data .................................................................................................... 8 4.2 Thermal Balance ...................................................................................................... 9 5 Data Collection ............................................................................................................ 12 6 Data Analysis & Results ............................................................................................. 24 7 Conclusions .................................................................................................................. 28 Appendix 1 ........................................................................................................................... 30 Appendix 2 ........................................................................................................................... 33 Appendix 3 ........................................................................................................................... 34 Appendix 4 ........................................................................................................................... 37 1 Introduction Ever since CFCs and HCFCs have been banned from use, the ozone layer has benefited from having a better regeneration capacity. It has improved so much that according to estimates, by mid-Century, the thickness of the ozone layer that shields us from the sun’s harmful UV rays, will be similar to what it was back in the 1970s. However, although CFC and HCFC replacements—known as HFCs or third- generation coolants—do not contain chloride, which destroys the ozone, despite their climate-friendly reputation, the fluoride contained within their molecule turns them into far more potent greenhouse gases, which in the end heat up the planet. Industry’s search for alternatives to these not-so-climate-friendly refrigerants has so far resulted in the widespread use of CO2 or carbon dioxide (R-744). Carbon dioxide is naturally found in the environment as a byproduct of living beings’ respiration, etc. It does not damage the ozone layer and has practically no effect on global warming. The main advantage of this gas is that it is available in the quantity required and anywhere around the world. In terms of its suitability as an HFC replacement, because of carbon dioxide’s physical and chemical properties, it is possible to reduce the size of equipment (smaller compressors, smaller piping diameters, etc.), even though working pressures are considerably greater (see Appendix 2). This study will focus on comparing two stores that use R-507 with two stores that use R-744. The Tottus supermarket chain has agreed to include its Tottus Vitacura store (R- 507) and its Tottus Alderete store (R-744) in this study. Both stores are located geographically close to one another, in Santiago’s Vitacura District. The Jumbo supermarket chain has also agreed to participate in this study with two stores: Jumbo El Llano (R-507) and Jumbo Valdivia (R-744). 3 2 Purpose of the Study 2.1 Purpose The purpose of this study is to compare the energy efficiency of two refrigeration systems using two different coolants—R507 and R-744—and subsequently determine which of the two systems is more functionally efficient from an energy perspective. To that end, gauges were installed at four stores belonging to two different supermarket chains (Tottus and Jumbo). The R-507 coolant will be used at Tottus’ Vitacura store, while the R-744 coolant will be used at its Alderete location. As for the participating Jumbo stores, R-744 will be used at its Valdivia location, while R-507 will be used at the El Llano store in Santiago. These stores were chosen to take part in this study from among all the other stores in both chains because they use refrigerants under comparison, and because they have monitoring systems that will allow for matching and standardizing study results. Moreover, in the case of Tottus, its two stores are located geographically close to one another, which facilitates the comparison since the exterior climate conditions are the same. Regarding Jumbo, as of the date of this study, its Valdivia store is the only store in the chain that uses R-744. It also happens to be the only Jumbo store in the entire city that is comparable in terms of installed cooling capacity, which is why Jumbo’s El Llano store was the other one chose to take part in the study. Data gathered will be used to calculate a System Coefficient of Performance (COPSI)1 for each supermarket, which is understood as the Installed Cooling Capacity divided by the Electric Power Consumed (kW of Installed Refrigeration/kW of Electricity Consumed). This parameter will be basis for determining and comparing the efficiency of each system. 2.2 Parameters Measured In order to meet the study’s objective, a series of parameters will be measured and recorded. These will be used to calculate the operational properties of each central cooling system, as well as electric power consumption and system performance. The following parameters must be taken into consideration and recorded, regardless of whether they are time variables or not: 1 See definition of COPSI in Appendix 1 herein. - Temperature on Sales Floor and Back Room (°C) - Relative Humidity on Sales Floor and Back Room (%) - Installed Cooling Capacity (kW) - Total Accumulated Energy Consumed (kWh) We will use the aforementioned parameters to calculate the COPSI by relating cooling and electric power capacity. Likewise, temperature and relative humidity on the sales floor, back rooms, reach-in and walk-in (lockers) coolers will be recorded in order to make cooler operating conditions as similar as possible. 2.3 Geographic Location This study entails measuring the parameters set forth under item 2.b) at the following four supermarkets located in Chile. • Tottus Vitacura: Av. Vitacura 9019, Vitacura, Metropolitan Region. • Tottus Alderete: Miguel Comas 1798, Vitacura, Metropolitan Region. • Jumbo El Llano: Llano Subercaseaux 3519, San Miguel, Metropolitan Region. • Jumbo Valdivia: Errázuriz 999, Valdivia, Los Ríos Region. 3 Implementation 3.1 Equipment Used There are several internationally recognized brands of refrigeration system operations and control equipment available on the Chilean market. The most widely used one in Chile is the Danish brand Danfoss, which is why it was chosen to supply the gauges used in this study. The equipment listed below was used to measure energy, temperature and relative humidity: • AK-SM880, central control system, is in charge of controlling the store’s cooling system. It also has an internal memory for storing information from every sensor hooked up to its network. This information may be downloaded for analysis. For the study’s purposes, the system was used to record electrical and environmental parameters (temperature and relative humidity). Figure 3.1. AK-SM880 Central Control Installed at Tottus Alderete • WattNode ModeBUS, WNC-3Y-480MB, uses coils to read the facilities’ electrical parameters, such as voltages and currents, which are then interpreted by the central control to calculate energy, power, etc. Figure 3.2. Picture of WattNode Gauge Installed at Tottus Alderete • AK-CM 101, a humidity and temperature data communication module used to send temperature and relative humidity readings, taken from sensors connected to the gauge, to the central control system. Figure 3.3. Referential Picture of a Danfoss Communication Module Furthermore, each supermarket has its own refrigeration facilities called central refrigeration, and its capacity is determined by the power of the compressors available for operation. This power is calculated on the basis of cooling demand, which is, in turn, determined by the manufacturer-given capacity and technical specifications of each store’s coolers/lockers, such as size, project type, rotation, etc. 3.2 Hardware Installation Equipment listed under letter b) was installed in the machine room at each supermarket in order to provide quick and easy access to periodically check equipment and collect data. Nuova Service’s technicians installed this equipment in keeping with current Chilean standards governing high and low-power electric facilities. Equipment was installed in October and November 2017,